#!/usr/bin/env bash
# PostgreSQL — the cluster half of the postgres cabinet: plain manifests, one replica on a PVC.
# Notes: docs/notes/addons.md
set -euo pipefail
cd "$(dirname "$0")/.."

source ./lib/config.sh
load_config

K="kubectl --context ${KUBECONTEXT}"
NS="${DATA_NAMESPACE:-data}"

$K get namespace "$NS" >/dev/null 2>&1 || $K create namespace "$NS"

# The password is generated once and then left alone, so re-running this does
# not rotate the credential out from under whatever is already connected.
if $K get secret -n "$NS" postgres >/dev/null 2>&1; then
    echo "  secret exists, keeping the current password"
else
    password=$(head -c 18 /dev/urandom | base64 | tr -d '/+=' | head -c 24)
    $K create secret generic postgres -n "$NS" \
        --from-literal=POSTGRES_DB="${POSTGRES_DB:-postgres}" \
        --from-literal=POSTGRES_USER="${POSTGRES_USER:-postgres}" \
        --from-literal=POSTGRES_PASSWORD="$password" >/dev/null
    echo "  generated a password (read it back with the command printed below)"
fi

echo "  applying manifests"
$K apply -n "$NS" -f - >/dev/null <<YAML
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data
spec:
  accessModes: [ReadWriteOnce]
  resources:
    requests:
      storage: ${POSTGRES_STORAGE:-2Gi}
---
apiVersion: v1
kind: Service
metadata:
  name: postgres
spec:
  selector:
    app: postgres
  ports:
    - port: 5432
      targetPort: 5432
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgres
spec:
  replicas: 1
  # One volume, one writer. Rolling would start a second pod against the same
  # PVC before the first exits, and Postgres refuses to share a data directory.
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
        - name: postgres
          image: ${POSTGRES_IMAGE}
          envFrom:
            - secretRef:
                name: postgres
          env:
            # The image initialises into the volume root otherwise, and a
            # lost+found from the PVC makes it refuse to initdb.
            - name: PGDATA
              value: /var/lib/postgresql/data/pgdata
          ports:
            - containerPort: 5432
          volumeMounts:
            - name: data
              mountPath: /var/lib/postgresql/data
          readinessProbe:
            exec:
              command: ["sh", "-c", "pg_isready -U \$POSTGRES_USER -d \$POSTGRES_DB"]
            initialDelaySeconds: 5
            periodSeconds: 5
          livenessProbe:
            exec:
              command: ["sh", "-c", "pg_isready -U \$POSTGRES_USER -d \$POSTGRES_DB"]
            initialDelaySeconds: 30
            periodSeconds: 15
      volumes:
        - name: data
          persistentVolumeClaim:
            claimName: postgres-data
YAML

echo "  waiting for postgres..."
$K rollout status deployment/postgres -n "$NS" --timeout=240s

echo "  in-cluster: postgres.${NS}.svc.cluster.local:5432"
echo "  password:   kubectl --context ${KUBECONTEXT} -n ${NS} get secret postgres -o jsonpath='{.data.POSTGRES_PASSWORD}' | base64 -d"